Hey, wait! what's the criteria here!?! "stairway" has been voted most consistantly #1 by Arbitron, (they are the folks who keep track of these things). But are we talking vocals....Robert Plant has an incredibly unique voice, but honestly, he goes flat and off key quite a bit, but hey, it just really works for him ,ya know! Eddie van halen has an incredible technique, but is eruption the greatest song of all time? Does Joe perry have the technical virtuosity to be considered "The greatest"? I love Ted Nugent's "Strangle hold" but "greatest"? Clapton's "Layla"? Beck's "Freeway jam"? Um...what about lyrical content? How about megadeth's "Symphony of destruction"? Triumph's "magic power"? Evenessence "going under"? Rush is an incredible progressive rock band "working man" Dream Theater is probably the ultimate progressive rock band "pull me under" Sheesh.....this is impossible!